The invention relates to an optical star coupler having tapered optical wave guides or fibers for branching in an optical transmission system. Star couplers are used, for example, in bus systems in optical information transmission networks.
German Offenlegungsschrift No. 3035858 discloses a star coupler comprising tapered fibers. Therein, the transition of modes which can no longer propagate in the fiber core into the fiber cladding is taken into account. However, a drawback remains in that undesirable coupling losses occur at butt-jointed ends of the tapered portions of the fibers, particularly if the diameters of the ends to be joined are not the same. This is applicable, notably, to asymmetrically constructed star couplers. Even when high-precision connection elements are used, such coupling losses can be reduced only slightly.